470 
DE. A. W. HOFMAX^r OX THE PHOSPHOEUS-BASES. 
SEEIES OF DIATOMIC COMPOUXDS. DIPHOSPHOXIOI COMPOEXDS. 
Salts of ETHYLEXE-nEXETHTL-DIPH0SPH0>'IOl. 
Dihromide . — The occurrence of this salt among the products of the action of dibro- 
mide of ethylene on triethylphosphine has already been mentioned in the mtroduction 
to the experimental part of the memoir. On bringing together the materials in the 
proportions indicated by the equation 
C, li, Br, + 2C6 P = H3, P, Br,, 
that is to say, one volume of dibromide of ethylene and three volumes of the phosphorus- 
base, the diatomic compound is obtained, nearly in t'Jie theoretical quantity. It is dis- 
tinguished from the monatomic product of the same reaction by its much greater solu- 
])ility even in absolute alcohol, from which it separates, only after almost complete 
evaporation, in needles which are permanent in the air. In ether this salt is insoluble, as 
are in fact most of the bromides of the phosphorus-bases, both monatomic and diatomic. 
The dibromide obtained by the direct action of dibromide of ethylene on tiiethylphos- 
phine always contains a small quantity of the monatomic bromide, from which it can 
only be purified with great difficulty. And further, if the dibromide of ethylene has 
not been carefully purified from adhering hydrobromic acid, the resultmg salt is hke- 
wise contaminated with traces of the extremely soluble hydrobromate of the phospho- 
rus-base, the presence of which likewise interferes very much ■u’ith the punfication of 
the product. Lastly, the formation of oxide of triethylphosphine can never be entmely 
avoided, even when the operation is conducted in an atmosphere of carbonic acid. To 
obviate these inconveniences, the compound submitted to analysis was prepared by 
saturating the hydrate, to be presently described, with hydrobromic acid. 
1. 0-4837 grin, of bromide gave 0-7091 grm. of carbonic acid and 0-3543 grm. of water. 
II. 0-4850 grm. of bromide gave 0-4300 grm. of bromide of silver. 
The simplest expression of these results is the formula 
Cy 11^7 P Br ; 
the formation of the compound, however, and its deportment, fully to be discussed in the 
following paragraphs, prove unmistakeably that this expression must be doubled, and 
that the weight and composition of the molecule of this body is represented by the 
formula 
Ci4 H34 P, Br.,. 
Tlieorv. 
Experimeut. 
^ 
r 
r 
I. 
'i 
II. 
Cl4 
168 
39-62 
39-98 
H34 
34 
8-02 
8-13 
P2 
62 
14-62 
Br, 
160 
37-74 
0 r i i 
424 
100-00 
